Recreational vehicle refrigerator efficiency device

ABSTRACT

An Electric device which improves Efficiency during warm weather in ammonia type refrigerators found in recreational vehicles. The system operates automatically to turn on a blower to dissipate heat from the refrigerator&#39;s condenser, and turns off automatically when the refrigerator is not being used, or when the refrigerator&#39;s thermostat cycles off.

The present invention relates to a recreational vehicle refrigeratorefficiency device. The device consists of the following components:

-   -   A sheet metal or plastic funnel that sits directly below        condenser coils to guide air thru condenser    -   A 12 volt box fan to create airflow, which is mounted in the        opening of funnel    -   A thermostat mounted on the boiler tube right before condenser,        that turns the fan on and off.

BACKGROUND OF INVENTION

Since the attacks on our country on Sep. 11, 2001, many Americans havepurchased RV'S as an alternative for vacations instead of flying. Mostof these RV'S have kitchens with refrigerators installed in them. Theserefrigerators are the ammonia absorption type. These units are reliable,being in existence for decades. They have no moving parts, and arepowered by 110 volt house current, LP gas, and or 12 volt DC.

A drawback, however, is these units depend on ambient air temperature tooperate. The higher the outside temperature, the less efficient the unitwill operate. This is caused by the condenser not being able to convertthe vapor ammonia supplied by the boiler entirely into a liquid. Theresult is a cold freezer, but the refrigerator section being warm,because there is not enough liquid ammonia being produced to keep therefrigerator section cold, resulting in spoiled food.

These refrigerators are installed in a compartment inside the RV. Mostapplications have a vent thru the roof, and also a louvered door outsidethe RV, at the bottom of the refrigerator compartment. Natural draftoccurs as cool air enters the lower louvered door and travels up behindthe refrigerator, passes across condenser, removes heat from condenser,and in most applications, exits thru the roof vent, although someapplications have an upper side vent instead of a roof vent.

During hot seasons, there is a need to force air thru the condenser toconvert the vapor ammonia into as much liquid as possible. Applicant isaware of devices on the market to move air around inside therefrigerator cavity, but none of these devices actually force airdirectly thru the condenser, where it is needed.

Applicant investigated the patent literature on this topic and thefollowing patents turned up during the course of a search:

-   -   U.S. Pat. No. 2,562,286 M. R. Wall    -   U.S. Pat. No. 2,705,404 H. S. Malutich    -   U.S. Pat. No. 2,734,441 E. C. Williams    -   U.S. Pat. No. 3,444,698 J. L. Lorenz    -   U.S. Pat. No. 3,717,010 Slattery    -   U.S. Pat. No. 4,864,269 Priebe    -   U.S. Pat. No. 5,228,307 Koce    -   U.S. Pat. No. 5,355,693 McConnell et al    -   U.S. Pat. No. 6,076,363 John C. Morton

None of these patents either singly or in combination anticipates orrenders obvious the subject matter of this invention. It is an objecttherefore to provide an automatic system that forces air thru thecondenser coils when unit needs to produce more liquid ammonia. It isanother object to provide a system that is universally retrofittable toexisting RV refrigerators. Other objects of the invention will in partbe obvious and will in part appear hereinafter.

The invention accordingly comprises the device possessing the featuresproperties and the relation of components which are exemplified in thefollowing detailed disclosure and the scope of the application of whichwill be indicated in the appended claims.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cutaway view of a refrigerator compartment in a typical RV,with the refrigerator therein, and the elements of this inventionrelative to the rear of the RV refrigerator.

FIG. 2 is a view of the invention with electrical components and wiring.

FIG. 3 is a side view of invention, relative to the rear ofrefrigerator.

SUMMARY OF THE INVENTION

A system comprising of a plenum with a high cubic feet per minute fanforcing air directly thru the condenser of a RV refrigerator todissipate heat to increase efficiency.

The system operates automatically to turn on and off as needed,regulated by boiler temperature. The system ceases to function when therefrigerator itself is turned off, or when the thermostat in therefrigerator is not calling for cooling. By forcing air thru thecondenser, which is a heat transfer device, allows the condenser todissipate more heat, thereby allowing the vapor ammonia to fully turnback into a liquid, thereby increasing the cooling capacity of therefrigerator.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1 there is seen a typical RV refrigerator, 1 which can vary incubic size. No matter the size, they all generally operate in the samemanner. That is they are powered by 110 volt house current at a RV park,or in remote areas off of 12 volt DC or LP gas.

Refrigerator is seen disposed within a compartment 4. The compartmenthas a spaced rear wall, and this is where the natural draft occurs tocool the condenser 7. Cool air enters lower louvered door 2 and warm airexits thru upper side louver 3 or more commonly out the roof vent 16. Onvery hot days the same draft occurs, but since the air temperature ishigher the condenser 7 can not cool down the hot ammonia vapor totally,thus not supplying the refrigerator with enough liquid ammonia. Sincethe refrigerator compartment is 2^(nd) in line to the freezercompartment, the refrigerator coils 14 have no liquid ammonia going intothem, resulting in no cooling.

To prevent this occurrence, condenser 15 is fitted with a plenumconstructed of thin gauge sheet metal or molded plastic 9 with a highcubic feet per minute box fan 8 mounted on bottom of plenum. Plenum isslid behind condenser coils 7 and attaches to rear of refrigerator via2-way tape and optional stand off bracket 17. A snap disc thermostat 11is mounted on vapor line coming out of boiler 5. Snap disc thermostat 11closes on temperature rise and opens on temperature fall. When boiler 5tube reaches a predetermined temperature, the snap disk thermostatcloses and sends 12-volt DC positive current from factory junction box 6on rear of refrigerator to the 12-volt DC positive line 12 of box fan 8.The negative 12-volt DC line 13 is attached to the 12-volt DC negativeline of box fan 8 and to the factory junction box 6 on rear ofrefrigerator and is not switched in any form. At this point the fanstarts and pulls air from lower louvered door 2 and forces it thruplenum 9 and condenser 7 and exits out upper louvered panel 3 or morecommonly out roof vent 16.

When the thermostat in refrigerator is satisfied and not calling for anycooling, or the refrigerator is shut off, the boiler 5 ceases to heatand the boiler 5 vapor line cools, and the snap disk thermostat 11opens, thereby breaking the 12-volt DC positive current 12 to box fan 8.

It is seen that there is nothing to set, nothing to forget. All oneneeds to do is to turn on the refrigerator and the invention will turnon automatically as needed.

In the event the snap disk thermostat 11 or box fan 8 fail, unit willstill operate, but will operate as if the invention was never installed,meaning no gain in efficiency.

The snap disk thermostat and box fan mentioned above are readilyavailable in the marketplace from several venders. Electrical currentconsumption of the box fan is small, as it would take weeks of constantrunning to drain a RV deep cycle battery.

It is seen that I have developed a system where air is forced directlythru the condenser coils of a RV refrigerator to improve efficiencyduring high temperature seasons, without the need to remember to turnthe system on or off.

I have several prototypes operating in the field, and a 30% increase inefficiency was noted.

Since certain changes may be made in the above device without departingfrom the scope of the invention herein involved, it is intended that allmatter contained in the above description, shall be interpreted asillustrative and not in a limiting sense.

1. An automatic switch controlled device which forces air via a box fanand plenum directly thru the condenser coils of a RV refrigerator,improving efficiency during hot seasons.
 2. The method of evacuatingheat generated from the operation of a RV refrigerator's condenser fromthe space between the refrigerator and the outside wall of the vehiclewhich comprises: Mounting a plenum and box fan to the condenser ofrefrigerator, and a snap disc thermostat to boiler tube, and usingexisting factory power point, automatically actuating the fan when saidsnap disk thermostat senses a rise in boiler tube temperature, andautomatically turning off when said snap disk thermostat senses a fallin boiler tube temperature.
 3. A universal device that is easilyadaptable to existing RV refrigerators.